The research of more than 2,300 undergraduates found 45 percent of students show no significant improvement in the key measures of critical thinking, complex reasoning and writing by the end of their sophomore years.

One problem is that students just aren’t asked to do much, according to findings in a new book, “Academically Adrift: Limited Learning on College Campuses.” Half of students did not take a single course requiring 20 pages of writing during their prior semester, and one-third did not take a single course requiring even 40 pages of reading per week.